Well, I haven't finished it yet, so I can't make too many claims

. Still, I will say that this book ..
.. is making more sense to me than the Ed Friedland (vol 1-3) books mentioned earlier on

. They were accurate and easy to follow, but ultimately didn't really tell me much about "how to write my own lines" (which is kind of what I was hoping to learn

).
The Gary Willis book puts scale usage into a very "useable" context (IMHO) and there's a good element of "adding your own input" to some of the excercises.
I's cheap enough - gotta be worth a look! Just my opinion

.